The invention applies in particular to the case of pots such as a typical pot made of plastic, waxed cardboard, or the like, and intended to be closed by a lid. The term “pot” should be understood in the broad sense as including actual pots, but also tubs, cups, or other similar forms of primary packaging. The items may be in the form of single pots or individual multipacks comprising multiple pots side by side and attached to each other while being arranged in columns and/or rows with frangible lines or areas of lower resistance between them. For example, a multipack may comprise two pots, or four pots arranged in two rows each containing two pots, or six pots in two rows each containing three pots, etc.
As detailed below, the invention applies to the case of separate multipacks but finds particular application to the case of items in the form of single pots, meaning individually separate and not attached in multipacks, said single pots being filled or not filled with content and closed or not closed by lids.
Such an item typically contains or is typically intended to contain a content, homogeneous or not homogeneous, having a general state that is more or less fluid, possibly containing more or less solid pieces. Such content is, for example, a milk product or a dessert, this list not being exhaustive.
For example, the invention finds particular application in the production of fresh milk products including those of very short shelf-life, such as yoghurts and the like, puddings, ice creams and the like, but also cheese products, compotes, etc. The invention also applies in the production of products of different types and/or destinations but which can be regarded as similar in terms of their conveyance in the production chain.
For the production of such products, a content to be packaged is made available or produced, pots and lids that are individual or arranged in multipacks are made available or produced, and individual wrapping blanks are made available or produced. Then the products themselves are made, meaning that the pots are filled with the desired content or contents and then the pots are closed by placing the lids. Then batches or packs are formed and if they include several pots, they are grouped together, for example stacked. Next, a wrapping blank is optionally placed around each pot, batch, or pack, which is folded and closed on itself. Then the items are boxed when appropriate.
Conveying machines enable the transport of items, meaning products at various stages of their production, between each of these operations. Items of a production line are understood to mean products at various stages of their production, including empty pots, filled pots, pots filled and closed, or pots filled and closed and wrapped.
Such a conveying machine comprises an infeed for an incoming batch of separate items, arranged on or in an incoming batch carrier, and an outfeed for items in a batch of outgoing items.
There are known conveying machines comprising a conveyor belt on which the items are advanced, the conveyor belt moving the items from one station to the next station. Such conveying devices have the disadvantage, during the conveying, of losing the information on the relative position and relative orientation of the items.
This information is essential in many cases for the later processing of the items, for example for sealing the pots, aligning the decoration, assembling into a batch or pack, wrapping or even boxing the items. It then becomes necessary to implement position and orientation sensing means and repositioning and/or reorienting means downstream of such conveying machines, which is complex and expensive.
Here, the term “information on the relative position” is understood to mean a knowledge of the position of an item relative to adjacent items and/or relative to a general reference system. In particular, it means information on the position of said item in a horizontal plane of the conveying machine, in particular a plane of general movement of the items to be conveyed.
The term “information on the relative orientation” is understood to mean a knowledge of the orientation of an item relative to adjacent items and/or relative to a general reference system. In particular, it means information on the orientation of said item on a vertical axis perpendicular to said horizontal plane of the conveying machine.
Also known are so-called “walking beam” conveyors, which are used to move items step by step while retaining at least some of the information on the relative position of the items, and possibly also on the relative orientation of the items, as indicated above. Such conveyors usually have a succession of bars mounted on camshafts, which by successively lifting the items allow them to advance, step by step, along the conveyor. Such “walking beam” conveyors have the disadvantage of being expensive, as they are composed of a large number of parts having synchronized movements, and are usually limited to the conveyance of individual pots.
FR 2,673,611 describes a conveyor following a rectangular cycle, taking items from a production station and placing said items on a conveyor belt. Because of the uncontrolled contact between the items and the conveyor belt, the items may bounce or pivot during placement. Here again, it is necessary to provide means for repositioning the items downstream of the conveying machine.
The problem underlying the invention is therefore to provide a method and a conveying machine which make it possible to save information on the relative position and the relative orientation of items during their conveyance so as to allow downstream processing of the items without preliminary repositioning. The invention also aims to provide such a method and such a conveying machine that are inexpensive and easily adaptable.